1.) Field of the Invention
This invention relates to an occupant-protecting seat belt system for a motor vehicle, and specifically to a passive seat belt system of the type that an occupant-restraining webbing is fastened to a slider and the slider travels along a rail mounted on a part of a vehicle body so as to cause the webbing to approach or recede from the body of an occupant.
2.) Description of the Related Art
In a conventional passive seat belt system, a slider and a drive member are connected and the slider is caused to move between an occupant-restraining position and an occupant-releasing position, for example, by the opening or closure of an associated door. There are a variety of methods for the connection of the slider and the drive member.
As is illustrated in FIG. 7 by way of example, a rail 50 defines a drive member channel 51, through which a drive member 10 extends, and a slider guide channel 52 along which a slider 40 moves.
The drive member 10 is composed of a wire 11, which is provided with drive blocks 20,21 and collars 30,31,32. The drive blocks 20,21 and collars 30,31,32 are arranged at suitable intervals. They are formed integrally with the wire 11. As an alternative, the wire is first caused to extends through them, followed by their fixing on the wire with self-locking nuts.
A webbing 71 is fastened to the slider 40 by way of an emergency release buckle (ERB) 60 and a tongue 70. An occupant is restrained or released in accordance with movements of the slider 40.
In the illustrated conventional passive seat belt system, the slider 40 is caused to move when the slider-contacting face 23 or 22 of the drive block 21 or 20 is brought into contact with a slider head 41, and the drive member is paid out or taken up by an unillustrated drive unit including a motor or the like.
In the above-described conventional example, the slider 40 is not fixed to the drive member 10 and is simply loose-fitted in the rail 50. When a force is applied to the slider 40 because of the roughness of an associated contacting surface, a variation in frictional resistance or the like and the slider 40 is swung, for example, upward or downward, a leading end face 42 or trailing end face 43 of the slider head 41 is brought into contact with the rail 50 (especially, an upper wall 53 of the slider guide channel 52. As a consequence, a frictional force is produced so that the smooth movement of the slider 40 is impaired or chattering or rattling noise and vibrations are developed (see FIG. 8).